Species of the week: birch polypore fungus

As part of National Fungus Day the British Mycological Society is asking people to take part in fungi spotting and let them know if you see the birch polypore. If you would like to hold an event as part of UK Fungus Day on the 12th October (part of Biology Week) please contact admin@britmycolsoc.info

Piptoporus betulinus, or the birch polypore, is a parasitic disease of birch trees. It’s a bracket fungus with a light brown tan upper surface, and underneath are the white pores which produce the spores. When birch polypore infects a tree, it leads to brown rot.

The fruit bodies (the brackets themselves) are often seen on dead or dying trees. This is because the fungus is a pathogen, and will eventually kill the tree. In the meantime though, the brackets provide a home and a source of food for a variety of different insect species, including mites and the caterpillars of the moth Nemaxera betulinella, also known as the golden-speckled clothes moth.

The birch polypore is also known as the ‘razor strop’ fungus, due to the practice of barbers using tough, leathery strips of the dried brackets to sharpen razors. It has also been used as tinder as it’s able to hold a flame for a long time. The fungus was used to start the Beltane festival fires in the Scottish Highlands.

Otzi, the mummified 5,000-year-old iceman found in the Tyrol, was found to be carrying two pieces of the birch polypore on a neck thong, and it’s though that he was carrying it for medical uses. The birch polypore was formally used to clear intestinal worms and it’s also a known anti-inflammatory. Modern analysis has revealed the fungus to contain ketones, terpenes and aliphatic alcohols, all of which contribute to the anti-inflammatory properties.

It can also be used as a styptic (a substance which can stop bleeding). In Sussex it was documented that the charcoal of the birch polypore was used as a disinfectant and antiseptic and that strips were used as a corn plaster.